Apparatus for peeling vegetables and fruits



March 17, 1953 o. PJPIERSON APPARATUS FOR FEELING VEGETABLES AND FRUITSOriginal Filed June 14, 1945 Patented Mar. 17, 1953 APPARATUS FORPEELING VEGETABLES AND FRUITS V 0101 P. Pierson, Caribou, Maine Originalapplication June 14, 1943, Serial No. 490,784. Divided and thisapplication August 27, 1948, Serial No. 46,416

4 Claims. (01. 14 -43) The present invention relates to apparatus forpeeling vegetables and fruits, and is particularly concerned with thepeeling of tubers and root crops, of which potatoes, beets and carrotsmay be taken as examples. This application is a division of my priorapplication, Serial No. 490,784 filed June 14, 1943, now abandoned.

When potatoes are to be prepared in quantity, as for foodmanufacturingoperations or in restaurants; the removal of the skins presents adifiicult problem. Various attempts at automatic" removal of skins havebeen proposed, such as chemical (lye) treatments and methods involvingabrasive action. The chemical methods have obvious disadvantages, andthe abrasive methods are unsuitable for potatoes of irregular shapes inthat they cannot succeed in loosening the skin in the neighborhood ofeyes or indentations; furthermore they necessarily cause excessivewastage of edible portions of the potatoes.

The principal object of the present invention is to present a simple,effective, and economical apparatus for removing the skins from potatoesand other vegetables and fruits. Since potatoes present the mostdiflicult problems, in view. of irregularities in shape and size and thetenacity of. the skin, the following description will be largely setforth in terms of potato peeling, butit .will be understood that it maybe applied to other food products for which generally similar conditionsprevail.

With this object in view, the principal feature of the present inventioncontemplates that the potatoes be subjected to the following steps: (1)exposure to high-pressure steam in a pressure chamber for a short time,and (2), spreading in a single layer to be subjected to a high velocitywater spray. The brief exposure to high pres-' sure serves to effect,such a conversion of the "body of the potato in the layer immediatelysubjacent to the skin asto cause a loosening of the bond between theskin and the potato proper. The principal feature of this step of thepresent invention resides in subjecting the potato to high temperatureand moisture for a very short time, suflicient to loosen the skin, butinsufficient for heat to penetrate the potato and cause softening of itsinterior. It hasbeen found that steam at a pressure of' at least 40pounds per square inch gauge is entirely satisfactory and that with thispressure the potato may be subjected to the treatment for only about30-to 45 seconds. If steam at a lower pressure werefused, acorrespo'ndinglylonger period would berequired to Without requiringadjustments for size. 7 ture of the present invention contemplatesappaloosen the skin and this would result in cooking of the interiorportion, with consequent loss of edible portions of the potato in thesubsequent tions of the kind usually considered as cooking,

since the object and effect of cooking are to soften the meat of thepotato to render it edi-' ble, while the present invention seeks topre-'- vent softening of the meat, except perhaps in a very small layerimmediately beneath the skin.

Following the steam treatment, high velocity water sprays are used toremove the softened and loosened skin, the potatoes being first spreadin a single layer while being conveyed to a discharge point. It isimperative that the spraying operation be conducted with the potatoes ina single 'layer in order that some of the potatoes will not mask 'orblock the others. It is furthermore essential that potatoes becontinuously turned during this operation to present all portions oftheir exterior surfaces to the spray. In view of the variation in sizesof potatoes, the conveying means is preferably such as'will effect themovement of the potatoes to the discharge point and their simultaneousturning motion A fearatus which accomplishes this result with potatoesof substantially any size and character.

In the accompanying drawings, I have shown apparatus from which the fullnature of my invention and its many novel features and advantages willbe readily apparent.

In the drawings Fig. 1 is a schematic view of apparatus in accordancewith my invention; Fig. 2 is a partly sectioned side view of oneembodiment of skin treating apparatus in accordance with my invention;Fig. 3 shows the apparatus of Fig.2 in end view; Fig. 4 is a fragmentaryview of the skin removing apparatus shown in Fig. 1 to illustrate partseliminated to simplify Fig. 1.

In accordance with my invention, I employ a pressure chamber In in whichthe potatoes or other objects are treated by steam under pressure, askin' removing unit II, and means such as the conveyor I2 to carry theobjects from the chamber H) to the unit II.

to the steam, they are continuously tiunbledto tory results may beobtained with the time of ex:-

posure being in the order of iorty-five seconds. With relatively newpotatoes; the time of ex.- posure may be further limited and I haveobtained good results in twenty to thirty seconds.

Because of the relative shortness of time required in accordance withmyinvention; the upper limits of pressure are determined by what is:

economical in a given set-up.

After the objects have been exposedto-the.

steam, the pressure is released and the potatoes are discharged in a,single; layer on. the..conveyorr and carried; to; the hopper- !3.of'thepeeling. unit.- H. which. they are. subjected toythe liquid.sprays; IA. The sprays i41 are'of, sufiicient force. toaIremovethe skinsof the thus treated potae toes. The potatoes are supported ,in' theunit. H='byradjacent'portions-of adjacent closely spaced rolls-l'5.. AsshowninFigA; partitions l6 serve to; hold'lthe-potatoes: or: other: objectsin contact with: the rolls: so that: each two adjacent rolls may beregarded: as defining a path for the potatoes. At least one: and:preferably both rolls defining each path: are positively rotated. Whereboth rollsare'positively rotatable, they may be driven at different?speeds and in; different directions. Whiletheirprimary function is torotate the potatoes. relatively rapidly, they may also have; an abradingaction due to. the relative rates: of rotation of the rolls, the typeof. covering; for the; rolls, orboth'.

Thepotatoes are advanced'along their paths: asby impellers l1, thefingers ofwhich are; suffi ci'entlynarrowand'rigid to passbetweentherolls; and advance the potatoes at a uniform. rate :with' a tumblingaction. Preferably, theimpellers I1 rotate slowly inrelation' to thespeed of the rollsso that while the-potatoes are exposed thoroughly anduniformly to the action: of the sprays, they:

are-rotated sufiiciently rapidly to avoid injury of the potatoes by theforce of the spray.

The apparatus I'll in which the potatoes are subject to the steammaybeof the batch typeas' showninFigs. 2' and 3.

As shownin Figs. 2 and 3, the; apparatus may consist of a frame I8having aline'd bearings [9' in which the spindles 2B; ZB on the ends'of"the retort 2! are journalled. A gear 22 fast on" thespin-dle 2'll mesheswith a pinion 23 on-the shaft 24' journalled in the frame IS. Theshafit' 24 has a' sprocket 25 connected" by a chain 26" to the sprocket2T driven by the motor 23 through aspeed reducing unit 29 associatedwith which isa control unit 29* which may be'a timing unit or may bemanually operated.

The-retort 2| has a hopper feed 3i! adapted to receive'the potatoes fromthe loader 3| on thedischarge end of thefeed 32, which may be aconveyor, chute; or the like. The hopper 38 has a cover 33 hinged as at34 to the retort 2i and the cover is adapted to be clamped. tightlythereto by locking earns 35 carried on support 36pivotallyconnected tothe retort 2 I Theirame l8" supports a discharge hopper 31 through whichthe potatoes? or other objects discharged. fromthe-retort-ZI are fedonto the conveyor l2. The hopper 31 is spaced sufficiently below theretort 2| to permit it to be rotated with the cover open. The lockingcams 35 may be released as the retort rotates when they are accessiblypositioned and the cover then opens under the influence of gravity oncontinued rotation of the retort to permit the: potatoes to be dumped.into thev hopper 3.1.. 1 form; the retort 2| with walls 38 to establisha discharge chute.

The pressure retort ha its end walls Zi tapering, outwardly towards thespindles 20, 20 andI employ apertured partitions 39 to separate the endportions of the retort 2| from the po-- ta'to receiving part thereof. Asteam pipe 40 which may serveas a brace for the retort extends-throughthe .spindle 20 through the bearing [9 and. to. the opposite end of theretort 2| and is sealed externally of the retort 2| by a suitably:packed joint w Steam ports 4| discharge steam into the steam receivingchambers defined. by; theretort ends. lie and. the partiti'ohsfifii Thepartitions: 39 maintain.- potatoes. skins and the like remoteafromthessteain ports. 4!: as the; ports; might. become clogged thereby;This: constructionalso has. the advantage of ensuring that the force of'the. admitted steam; is dissipatedbefore it'contacts; the potatoes.

Steamfrom: any suitablesourceis admitted to-the'pipe 4:0 by'suitablemea-nssuch as shown:-

whistle? type: which. permits quick and. easyoperation. A likevalve4'8'is disposedto quickly and easily control the deliveryrofsteamthrough; the main delivery conduit. 42? at 49' a conventional.steam' traps in: the steam: delivery system.

The exhaust-system consists of a main exhaust conduit 50" controlled" bya whistle valve 51-. and of" suificient size to permit the pressure inthe retort to be relieved. quickly. The exhaust: system also: includesa. parallel conduit 52" con'.- trolled bya pressure relief valve 53'ensuring themaintenanceof desired pressure in the retort 21 until thedelivery system is-shut 'ofi an'd"the" ex"-- haustvalve 51 is'openediSteampressure gauges: are shown at 54;

The operation so far as understood, is described as follows: Thepotatoes aresubjected in the retort lflto theaction: of the' highpressure steam. Since steam: at forty pounds per square inchgaugepressure hasa temperatureof'about- 287 if, theexterior portionsofthe potatoes areiifn mediatelysubjected to an intense superficial"moist heat. Theacti'on is not' fully understood", but it is believed todepend to some extent on' hydrolysis in the skin and in avery'thinlayer' just beneath the skin. Theme of steam is essen-- tialfor hydrolysis, as distinguished from the use of dry heat which wouldtend to toughen the skin. Also, as heretofore noted, treatment atsuperatmospheric pressure is essential since at lower pressures andtemperatures the-treatment must be prolonged to such an extent that theheat will penetrate into the interior andwill thereforeefiectasubstantial cooking" of themeat" with the result that under later:action: by the water spray, aconsiderable portion ofthe meat willbecarried away.

During the steam treating operationthe retort. is-slowly rotated. Thiscauses a-tumbling action of the potatoes. The tumbling action resultslnhave indicated:

in some abrasion of the skin by reason of contact between the potatoesthemselves. 1 The skin removal in this stage is,-however, not complete.and-cannot be made complete without holding the potatoes at hightemperature for too long a time. The object of the tumbling is primarilyto insure that all of the potatoes are uniformily subjected to the steamtreatment.

In general the pressure (and hence the steam temperature) should be ashigh as possible consistent with safe and economical design of theequipment. An increase in pressure requires a reduction of exposure timeand it is apparent that the shorter the time of exposure the less willbe the penetration of heat into the interior. For some grades ofpotatoes, which have a particularly tough and tenacious skin, theexposure time will necessarily be longer than for new pctatoes withtender skin. It is impossible to state the optimum temperature and timecondition for all cases in view of these variations, but in any case thehighest available pressure (and hence temperature) is to be used, theexposure time is readily determined as that which will effect thedesired superficial action, without substantial softening of theinterior portions.

The potatoes after having been subjected to the action of the steam aredumped on to the conveyor 12 and carried into the peeling unit Hwherein, as heretofore noted, they are spread into a single layer andconveyed through the apparatus. It will be observed that adjacent rollsl5 serve to define the path of advancing movement of the potatoes whilecontinuously turning or rotating them. Furthermore, the potatoes, duringthe advancing and turning movements, are freely supported by the rolls;by this is meant that the potatoes are mainly supported from beneath,and are not engaged by any side belts or other holding means that mightimpede or obstruct the sprays, or might require adjustment for size. Byspreading out into a single layer on the unit II, the potatoes areindividually advanced by the impellers I! and are turned over and overby the action of the rolls 15. This advancing and turning operationtakes place regardless of the size or type of the potatoes themselves.The water spray should be a high-velocity spray in order to effectsubstantial removal of the skin and also to dig out the skin from theindentations or eyes. For this reason the water spray should be under afairly high pressure, say from sixty to eighty pounds per square inch.

It has been found that the present invention results in substantialremoval of skin even from potatoes-of unusual shapes, such as dumbbellshapes which are sometimes encountered. The invention is also applicableto other tubers and to root crops such as beets and carrots and even tosome fruits which have a firm meat, for example, apples. In any case theinvention contemplates the softening and loosening of the skin byconversion of the immediately subjacent layer without substantialpenetration of heat into the interior followed by the eroding action ofhigh-velocity water sprays while the vegetables are being conveyed in asingle layer toward a discharge point, and simultaneously are beingcontinuously rotated to present all portions of their exterior surfacesto the spray.

Having thus described my invention, I claim:

1. In apparatus for treating skin-covered v articles of food to loosenthe bond between their skins and their subjacent portions, a drum toreceive the articles, means for rotating said drum to tumble thearticles therein, a transverse partition wall extending across said drumnear an end thereof and together with the side andthe adjacent end wallof the drum providing a steam chamber in said end of the drum separatefrom the article-accommodating portion of the drum, a steam supply pipeextending substantially centrally of said drum into said chamber andhaving at least one lateral opening for discharge of steam laterallyinto said chamber, said partition wall having therein only smallopenings for the admission of steam from said chamber into thearticle-accommodating portion of the drum, thereby to insure dissipationof the force of the steam prior to its contact with the articles.

2. Apparatus as set forth in claim 1 in whic the end wall of the drumdefining the outer end of the steam chamber is inclined in a directionto deflect the steam delivered laterally into said chamber toward thepartition wall defining the inner end of said chamber.

3. In apparatus for treating skin-covered articles of food to loosen thebond between their skins and their subjacent portions, a drum to receivethe articles, means for rotating said drum to tumble the articlestherein, a transverse partition wall extending across said drum neareach end thereof and thereby providing in each end of said drum a steamchamber separate from the medial article-accommodatin portion of thedrum, a steam supply pipe extendin substantially axially of said drumand having lateral openings for discharge of steam laterally into eachof said chambers, said partition walls having therein only smallopenings for the admission of steam from said chambers into thearticle-accommodating central portion of said drum, thereby to insuredissipation of the force of the steam prior to its contact with thearticles.

4. Apparatus as set forth in claim 3 in which the end walls of the drumare inclined in directions to deflect the steam delivered laterally intothe steam chambers toward the partition walls defining the inner ends ofsaid chambers.

OLOF P. PIERSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

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